security/sudo: Remove dependency on security/sssd

security/sssd was removed from ports recently, which broke
the SSSD option. Let's remove the SSSD option and let users
use SSSD2 instead.

PORTREVISION has been bumped so it is easier to tell which
version of the sudo package supports only sssd2.

PR: 283952
Sponsored by: Klara, Inc.
Approved by: 0mp (mentor)
Approved by: garga (maintainer)
Differential Revision: https://reviews.freebsd.org/D48389